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Dieters May Lose Bone Density

Women who consistently limit what they eat to avoid gaining weight may undermine the health of their bones, according to a new study by ARS researchers in California. The study looked at the eating behavior of 192 women volunteers between the ages of 18 and 50.

Those classified as restrained eaters had significantly lower bone mineral density and bone mineral content than women who said they weren't concerned about what they ate. These two bone mineral measurements are key indicators of overall bone strength and health, according to physiologist Marta D. Van Loan and chemist Nancy L. Keim of the ARS Western Human Nutrition Research Center in San Francisco.

The study "provides new evidence that women who habitually worry about what they eat—to meet a target weight that they've imposed upon themselves or that they think our image-conscious society demands—may increase their chances of developing osteoporosis," says Van Loan.

A thinning and weakening of bone, osteoporosis increases the risk of fractures, particularly of the hip and spine. Spinal fractures are painful and may result in debilitating curvature of the spine.

Van Loan and Keim used a DEXA device—a dual energy x-ray absorptiometer—to measure bone mineral content and density. They administered a standard test known as a Three-Factor Eating Inventory to determine if volunteers were always overly concerned about what they ate, as is typical of restrained eaters.

"As far as we know," Van Loan says, "our study is one of the first of its kind to demonstrate a significant association between restricted food intake and either bone mineral content or bone mineral density."

"Exercise and eating a well-balanced diet with adequate calcium," says Van Loan, "are two of the best ways to keep your bones strong and healthy." Foods that are a good source of calcium include cheese, milk, ice cream, baked beans and other dried legumes, dried figs, broccoli, most dark-green leafy vegetables, and soft fish bones like those in canned salmon.

"Exercise that increases the force or load on your skeleton, such as jogging, lifting weights, or working out with resistance-type gym equipment," notes researcher Keim, "also helps keep bones from becoming brittle and porous."—By Marcia Wood, Agricultural Research Service Information Staff.

Marta D. Van Loan and Nancy L. Keim are with the USDA-ARS Western Human Nutrition Research Center, P.O. Box 29997, Presidio of San Francisco, CA 94129; phone (415) 556-9697, fax (415) 556-1432.

"Dieters May Lose Bone Density" was published in the April 1999 issue of Agricultural Research magazine.